Today in Science History – March 13 – Joseph Priestley

March 13 is Joseph Priestley’s birthday. Priestley was an English theologian and natural philosopher who is best known for his experimental works with gases or “airs”.

For centuries, the air was just the air. It was one of the main four elements of earth, air, water, and fire. Air was a simple substance, indestructible and unchanging. Scientists of the late 18th century began to take a closer look. They found air was actually a mixture of multiple distinct airs. Priestley found one air that greatly increased the process of burning.

The prevailing theory of the time believed things burned because of a substance present in all things called phlogiston. Things gained phlogiston as they burned. Once they became saturated with phlogiston, they stopped burning. Since his new air helped things burn better, it did not contain phlogiston. He called it “dephlogisticated air”. Even though his discovery seemed to support the phlogiston theory, it was one of the key elements to launch Lavoisier’s chemical reaction theories that started the chemical revolution of the 19th Century. Lavoisier also changed the name of this air to oxygen.

Priestley began his work with gases with a ready supply of phlogisticated air or carbon dioxide. He obtained near limitless supplies from a brewery near his ministry. One of the most notable achievements from this was a process to easily create carbonated water. He discovered he could produce this gas by dissolving chalk in acid and when he added this to water, he found it had a distinctive tangy taste. He called his drink soda water. This invention earned him an invitation to join the French Academy of Sciences and the Royal Society’s Copley Medal.

Priestly was also one of the first to observe photosynthesis but did not recognize what he saw. He put a green plant into a covered container of water and burned a candle. Eventually, the candle went out. After a while, he found he could re-light the candle.

Priestley was very outspoken in his support for the French and American revolutions. Since this position wasn’t very popular in his home country of England, he was forced to relocate to the new United States in 1794.

Notable Science History Events for March 13

1937 – Elihu Thomson died.

Elihu Thomson (1853 – 1937)

Thompson was a prolific inventor with over 700 patents including the invention of electric arc welding. He was the founder of Thomson-Houston Electric Company which merged with Thomas Edison’s company to become the General Electric Company.

1933 – Robert T. A. Innes died.

Robert Thorburn Ayton Innes (1861 – 1933)

Innes was a Scottish astronomer who discovered Proxima Centauri, the star closest to Earth. Over the course of his career, he discovered 1600 double star systems. He also converted a Johannesburg, South Africa meteorological station into the astronomical observatory known as Union Observatory.

1899 – John H. Van Vleck was born.

Vleck was an American physicist who shares the 1977 Nobel Prize in Physics with Philip Anderson and Nevill Mott for their research into the behavior of electrons in magnetic non-crystalline solids. He also proposed a model describing the electronic structure of transition metal compounds known as crystal field theory. This would eventually become the basis of ligand field theory.

1855 – Percival Lowell was born.

Lowell was an American astronomer who founded Lowell Observatory in Arizona. He predicted the existence of Pluto. He published three books on Mars that attempted to prove the thin lines on Mars’ surface were water canals and supported life. He also mapped a system of spokes and dark central hub on the surface of Venus. Today we know the surface of Venus cannot be seen from Earth.

Lowell also theorized the existence of a Planet X outside the orbit of Neptune. He believed a large mass was affecting the orbits of Uranus and Neptune and began a systematic search. He would never discover his planet, but Clyde Tombaugh would discover Pluto at Lowell Observatory in 1930.

1781 – William Herschel discovers the planet Uranus.

Uranus as photographed by Voyager 2.NASA

Hershel discovered an unusually shaped disk while surveying a section of stars he initially believed was a comet. He made a series of observations to keep track of his new comet and discovered it was a planet which had an orbit that was just outside the orbit of Saturn.